Crankcase compression, two-cycle engine



July 20, 1948*.

Filed Nov. 12, 1946 .1. s. JENNINGS 2,445,715

CRANKCASE COMPRESSION, TWO-CYCLE ENGINE I5 Sheets-Sheet 1 2.; 38 a willI4 14 .f/ I 4 37 3 1 (farms S. ciennzn ys July 20, 1948. J. SFJE NNINGSCRANKCASE COMPRESSION, TWO-CYCLE ENGINE 3 Sheets-Sheet 2 Filed Nov. 12,1946 Emma 3mm Jarvzs Sclnn in ys ,MA'W

July 20, 1948. ENNI 2,445,715

CRANKCASE COMPRESSION, TWO-CYCLE ENGINE Filed Nov. 12, 1946 3Sheets-Sheet 3 elliliieze.

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Jarvis xlmrzil zys Patented July 20, 1948 CRANKCASE COMPRESSION,TWO-CYCLE ENG Jarvis S. Jennings, Chicago, Ill., assignor to HooiProducts Company, Chicago, 111., a corporation of Illinois ApplicationNovember 12, 1946, Serial No. 709,127

11 Claims.

This invention has to do with internal combustion engines.

As here shown it is developed with a two-cycle type of engine, primarilydesigned for model airplanes. It will be understood, however, thatfeatures adaptable to types of engines and airplanes other than thespeciflc example here shown are not restricted to the particularadaptation herein disclosed.

More particularly the present disclosure relates to the make-up of theengine cylinder and crank case, which are so developed that they form amulti-part construction preferably made up of an integrally formedopen-topped cylinder jacket and open-sided crank case member,independent side plates being provided to enclose the crank case andcylinder jacket members. Such independently formed side plates are soconstructed that not only do they effectively close the crank case toform a suitable compression chamber, but also provide fuel feed passagesof small crosssectional area from the chamber to the combustion cylinderwhich is associated with the Jacket, eliminating the necessity of coringor drilling such passages.

A further feature of the invention is the provision of an independentreadily detachable closed-top combustion cylinder member, insertable inthe open-topped cylinder jacket member, which latter may be castintegrally with the crank case member, said closed-top cylindercombustion member being formed to receive the piston; the spark plug,and finned to give proper cooling areas. Suitable inlet and exhaustpassages are provided in the cylinder walls, these passages being sodisposed relative to one another that minimum interference between feedof fresh fuel and burnt gases results, and proper scavenging is secured.

Another object is the provision of a piston which will control inlet andexhaust ports and direct the fuel flow, and the make-up of which is suchas to provide a convenient and novel coupling of piston; pitman, andcrank-shaft.

Valve mechanism for controlling fuel flow from a fuel supply to thecompression chamber of the crank case, is pivotally mounted on a sideplate. and so coupled to the crank-shaft as to give a simple, readilyformed, and assembled construction. The mounting of the valve on theside plate is such that trapping of fuel in the valve and possibleexplosion of such trapped fuel is avoided, the entire volume of fuelpassing to the compression chamber.

These and other objects will be set forth more 2 in detail in thedescription which follows, reference being had to the accompanyingdrawings, in which:

Figure 1 is a view in side elevation of an engine embodying one physicalform of the invention.

Figure 2 is a view in vertical section of the engine shown in Figure 1.

Figure 3 is a view in horizontal section substantially on the line 3-3,Fig. 1, looking in the direction of the arrows.

Figure 4 is a view in vertical section substantially on the line 4-4,Fig. 2, looking in the direction of the arrows.

Figure 5 is an enlarged vertical section of the closed-top cylindermember.

Figure 6 is an enlarged horizontal section on substantially the line$--8 of Fig. 5.

Figure 7 is a view in perspective of a side plate, showing a fuelpassage; the valve seat and mounting on the side plate, and the valve.

Figure 8 is a view in perspective to show the top of the jacket.

Figure 9 is a view of the piston, partly in section, showing the fueldirecting recesses, the wrist pin, and spring rings for attaching thepitman.

Figure 10 is a view in perspective to show the crank pin key forengaging the fuel control valve.

Figure 11 is a perspective view of the wrist pin for the piston and theclamping rings.

Figure 12 is a detail view of the bolt for securing the combustioncylinder and jacket together.

The parts shown in the drawings will be designated by numbers, the samenumbers indicating the same parts in the different views.

Referring to the jacket cylinder and crank case, these as here shown,are made up of four pieces. The crank case ill and an open-topped outercylinder jacket I l are preferably of integral formation and the crankcase in has open sides. A closed top combustion cylinder l2 telescopesin the jacket II and forms the combustion chamber, as best shown inFigs. 2 and 4. This cylinder may be formed relatively thin, as it isreinforced by the jacket I I, and its upper part at top and side will beprovided with cooling fins ii. The fins l2 will be deeply cut close tothe cylinder wall and top so as to ensure rapid radiation through thethin cylinder wall and eiiicient cooling. The thin sleeve-like cylinderI! will be of material having highresistance so as to withstand theusual internal pressures.

The cylinder i2 is secured to the jacket II by means of a horizontalflange II projecting outwardly from the wall of cylinder member 12,

said flange being provided with bayonet, slots l4, through which passheaded bolts I5, four being here shown, which are threaded into suitablebolt holes l6 formed in the outer cylinder jacket H just above theexhaust outlets I4 which extend outwardly from jacket II. The outlets llare preferably oval in cross section to reduce their outer dimension andyet give sufficient exhaust area, and are ribbed or finned for cooling.This connection between jacket II and member I2 provides for easyassembling and disassem 'bling of the crank case, jacket, piston, andcombustion cylinder member, so that the parts may be initially puttogether, taken down for inspection or repair, and reassembled with aminimum of effort; The assemblage is such, however, that a secure andstrong structure results which will stand up under the work to beperformed and a fluid tight construction is assured.

The open-sidedcrank case Ill and jacket II are closed by side plates I'Ifitted in place and held by screws-or other suitable fastening means.Screws I8 engage the upper ends of the plates H with the jacket II,while through bolts I9 traversing spacing sleeves between side platesI1, hold the lower cylindrical portions of the side plate members I!together. This arrangement effectively completes the make-up of theengine housing and provides a sealed compression chamber and combustioncylinder.

The side plates I1 have open recesses on their inner faces to form fuelpassages. 2i of small cross sectional area leading from the crank caseupwardly. The lower ends of passages 2i communicate with inlet openings22 to admit fuel from .the crank case compression chamber. At the upperends of passages 2|, fuel delivering ports 23 are provided throughjacket II and the thin wall of the telescoped cylinder member I2 topermit delivery of fuel to the explosion chamher. With this constructionit will be seen that side plates II, when assembled with crank case I 3;cylinder jacket H, and combustion cylinder member I2, provide a completeengine structure. Further, by forming the recesses 2| on the faces ofplates H to provide, when assembled with the other parts, suitable fuelfeed passages, all coring or drilling of feed passages is avoided. Thecrank case; cylinder jacket, and side plates can be cast or formed inany suitable manner, and readily assembled to complete the unit.

. Disposed substantially at right angles to the opposed fuel deliveryports 23 are exhaust ports fuel and the relation of the inlet andexhaust ports effectively completes scavenging and charging withoutundue mixing of burnt products and fresh fuel, and loss of part of thecharge through the exhaust ports.

The piston is made up of thin stamped members. The outer member 25constituting the piston proper and fitting the cylinder, the innermember 26 being secured by riveting or in any other suitable manner tomember 25 and engaged with the pitman 21 by a hollow wrist pin 28suitably held in place by spring rings 28. This combination gives alight but rigid position which may be readily stamped up from sheetmetal.

24, slightly above the fuel inlets 23, so that they will be uncovered bythe piston just in advance of the uncovering of fuel inlets 23, whichexhaust ports 24 deliver to the exhaust vpipes I4 extending outwardlyfrom the cylinder.

With this construction, as arranged in the twocycle engine shown, theupward thrust of the piston draws fuel into the crank case andcompresses the charge above the piston for ignition and the powerstroke. Explosion of the charge in the combustion cylinder effects thepower stroke, forcing .the piston downwardly and first opening theexhaust ports 24. scavenging will begin immediately the exhaust portsare opened, the exhaust ports being uncovered in advance of the inletports 23. Fresh fuel entering ports 23 will be so directed upwardly fromthe piston, presently to be described, that the fuel jets from ports 23will follow the vertical wall of cylinder I2 to the fiat cylinder topand will then spread inwardly and turn back centrally of the cylindertoward the piston. This action of the incoming To effect proper fueldistribution, the top of the piston member 25 is provided with recesses29 which preferalbly are closed at their ends and may be partiallyformed, as shown in Figure '9, in projections 29. These recessescoincide with the fuel inlets 23 and will accurately define and directjets of fuel coming from the inlets upwardly in the combustion chamber.These f-uel jets will follow well defined paths along the wall of thecylinder and meet at the top of the chamber where they combine, spread,and turn downwardly to form the explosive charge, which charge isignited by any suitable ignition member such as spark plug 30.

Fuel is supplied to the compression chamber of crank case ID, by aninlet 3| from any suitable carbureting devices (not shown) and inlet 3|is controlled by valve 32 pivoted on a side plate I1. Valve 32 has anarc-shaped port 34 which, as valve 32 revolves, opens the inlet 3| andpermits fuel to be drawn into the compression space of the crank case.Movement of the valve 32 is so timed and related to the valve operatingmeans that it closes and opens at points appreciably past dead centersfor the up and down limits for the piston stroke. Valve 32 is coupled tothe crank pin 35 projecting from the crank disc, crank pin 35 being hereshown as integral with crank disk 36, and of hollow construction so asto lighten it while still maintaining the requisite strength. The outeropen end pin 35 is .milled oil to form a projection or key 31 whichengages a notch 38 in the rim of valve 32 when the parts are assembled.This gives an easily formed, efficient valve drive with a minimum ofparts and of light construction. Lightening of the parts, withoutsacrificing strength 01' efficiency is of great importance in thedevelopment of airplane engines. This is particularly true of enginesfor model plane construction where weight must be reduced as much aspossible to permit maximum fuel load capacity. The crank and propellershaft 39 are preferably drilled, as shown, for lightness. Valve 32 has-a pivot pin 40 of considerable length engaging the side plate II inorder to give it'an extended bearing in the side plate and ensureexactness of rotary movement in opening and closing fuel inlet 3i. Thepiston and crank pin will be coupled by a pitman of any usual orsuitable construction.

The valve 32 takes its bearing on a seat 4| made up of the raised outeredge of the side plate and the centrally disposed seating member, asshown in Fig. 7, this bearing surface being of such shape and size as toprovide a proper surface to support valve 32 in its rotary movements andyet reduce frictional contact. This raised seat 4| holds the valve 32slightly spaced from the body surface of side plate ll, but as thisinterspace I2 is in open communication with the recesses forming theinlet passages 2|, no

trapping of fuel coming from inlet 3| behind valve 32 can occur.

A timer '1, is conventionally shown, but as this forms no part of thepresent invention and may be of any suitable type, no detaileddescription of it is necessary.

This disclosure is of one particular embodiment of the invention, but itis to be understood that such variations from what is here shown as arewithin the skill of the mechanic and are comprehended by the appendedclaims, are to be regarded as within the range of the invention.

I claim:

1. An internal combustion engine comprising a cylinder jacket member andcrank case, said jacket having an open top and inlet and exhaust ports;a closed-top combustion cylinder engaged with said jacket and havinginlet and exhaust ports registering with the ports in said jacket;detachable side plates having fuel feeding passages on their inner facesleading from a compression chamber in said crank case to said combustioncylinder; a crank shaft coupled to said piston; means for supplying fuelto the compression chamber in said crank case, and a valve actuated fromsaid crank shaft to open and close the port from said fuel supply to thecrank case compression chamber.

2. The invention as defined in claim 1 in which the crank case has opensides and the detachable side plates close said open sides of the crankcase.

3. The invention as defined in claim 1 in which the cylinder jacketmember and the open-sided crank case are integral.

4. The invention as defined in claim 1 in which the combustion cylinderis telescopically engaged with said jacket.

5. The invention as defined in claim 1 in which the combustion cylinderis telescopically engaged interiorly of said jacket.

6. The invention as defined in claim 1 in which the combustion cylinderis provided with means for detachably connecting it tosaid jacket.

7. An internal combustion engine comprising I a cylinder jacket member;an open-sided crank case having inlet and exhaust ports; a closedfacesleading from a compression chamber in said crank case to said combustioncylinder, a piston controlling the inlet and outlet ports, a crank shaftcoupled to said piston, means for supplying fuel to a compressionchamber in said crank case, and a valve actuated from said crank shaftto open and 'close the port from said fuel supply means to the crankcase compression chamber.

8. The invention as definedin claim 7 in which the means detachablyconnecting said combustion cylinder and said jacket comprises a bayonetjoint.

9. An internal combustion engine comprising a combustion chamber, apiston in said chamber, a crank case having a compression chamber and anopen side, a crank shaft, a crank pin on said shaft, a pitman couplingsaid pin and piston,a detachable side plate having a fuel feeding recesson its inner face and a fuel inlet closing the open side of said crankcase and connecting the compression chamber of said crank case with saidcombustion chamber, and a rotary valve actuated by said crank pinmounted on said side plate to control the fuel inlet.

10. A detachable side plate for closing an opensided compression chamberof an internal combustion engine having a fuel inlet and a fuel feedingrecess on its inner face. I

11. A detachable side plate for closing an opensided compression chamberof an internal combustion engine having a fuel inlet, a fuel receivingrecess and a fuel feeding recess on its inner face, and a rotary inletcontrol valve pivotally mounted on the side plate in the fuel receiving.mavrs s. JENNINGS.

REFERENCES crrEn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS France 1907

